Determination of Cd, Mn, Sb, Ni and Fe in water samples after preconcentration on bentonite modified with trioctyl phosphine oxide

Bentonite modified by the addition of trioctyl phosphine oxide (TO-B) is developed for the separation and preconcentration of Cd, Mn, Sb, Ni and Fe, prior to their determination by flame atomic absorption spectrometry (FAAS). Separation and preconcentration of the above metals have been investigated by a column method using, TO-B as adsorbent, and analytes were quantitatively retained at pH 6.0. The elements collected were completely recovered with 1 mol/L of nitric acid. Low blank values of the collector have served as important advantage, and recoveries were 98.3%, 98.6%, 100%, 98.1% and 100% for Cd, Mn, Sb, Ni and Fe, respectively. The relative standard deviations were found to be 1.0-4.0%. Detection limits (3 sigma) were 0.25 mu g L-1 for Cd, 0.19 mu g L-1 for Mn, 2.3 mu g L-1 for Sb, 0.17 mu g L-1 for Ni and 0.12 mu g L-1 for Fe. The method was practically applied analysing the studied elements in wastewaters. The method can be characterized with fastness, simplicity, quantitative recovery, and high reproducibility.